The present invention relates to a movement joint.
Structural movement between individual parts of a building can and often does occur particularly in large buildings. The integrity of the building is seldom threatened, provided that it is adequately designed. However unsightly cracking in floors and walls in particular can be avoided by providing a movement joint known as a xe2x80x9cfield limitation jointxe2x80x9d in the finish layer of these surfaces. Generally such a joint includes a flexible member which is able to expand and compress with movement of the substrate layer(s) beneath the finish layer. The joint may induce cracking of the substrate along its length, whereby the finish layer does not crack, but can move as a block with respect to one or more adjacent blocks separated by the joint or several joints.
The object of the present invention is to provide a method of fitting a field limitation joint to a faced floor or wall and to provided an improved field limitation joint.
According to one aspect of the invention there is provided a method of fitting a field limitation joint to a faced floor or wall, the joint having a Y cross-section with compressible material in the space between the divergent upper limbs of the Y, the method consisting in the steps of:
laying a hardenable bed on the floor or wall,
setting flat facing members on the hardenable bed in an array, with a defined field limitation line at a gap between certain of the arrayed members, the gap having a defined width, which is less than the free width of at least the distal ends of the upper limbs of the Y,
inserting the field limitation joint into one of the gaps to a depth such that upper limbs of Y rest on the facing members at the gap and the joint protrudes proud of the facing members and
driving the joint into the gap until its top is flush with the surface of the facing members, the lower limb of the Y penetrating the hardenable bed, the upper limbs of the Y being displaced towards each other with the compressible material between the upper limbs being compressed.
Preferably, the spaces between the facing members which are not to receive a joint are grouted prior to fitting of the joint.
In one procedure, the hardenable bed is cut along the field limitation line prior to inserting of the joint, the cut preferably having adhesive applied into it. Alternatively, the hardenable bed is cut by the field limitation joint being inserted into the gap between the facing members.
Preferably, the gaps defining the field limitation lines are regulated by laying the facing members along the lines with a spacer of a defined width therebetween. Usually, the spacer is removed prior to insertion of the joint.
In the preferred embodiment, the spacer is a portion of the joint, which is narrower than the free width of the upper limbs of the Y. preferably a lateral swelling at the junction of the Y, the joint being driven home once the members along it have been stabilised by at least partial hardening of the bed and/or grouting oft hem.
Preferably, all the facing members are spaced identically and the joint has a compressed width equal to the spacing of the tiles which are grouted.
According to another aspect of the invention there is provided a field limitation joint for the method of the first aspect of the invention, the joint comprising
a core of relatively compressible material and
side members of relatively incompressible material, the side members having the core bonded or otherwise affixed between them and abutting the facing members when driven between them,
a downwards extension of the side members beneath the core with the side members unified or abutting in the extension,
the side members and the extension defining a divergent Y-shape in cross-section, when free of abutment with the facing members prior to driving, the side members being upper limbs of the Y and the extension the lower limb of the Y
whereby on fitting of the movement joint into a field limitation gap between facing members which is narrower than the width of the joint at the distal ends of the Y, they at least are compressed between the facing members.
In one embodiment, the core is an elastomeric insert and the side members are metallic, The metal side members can be welded together in the lower limb of the Y. Alternatively, the metal side plates are rolled from a single strip and bent double at the bottom of the lower limb of the Y. In either alternative, the elastomeric insert can have a lower rib connected to an upper strip by a thinner section, the metal side plates being rolled to shape to captivate the lower rib. In this case, the elastomeric insert is conveniently a co-extrusion of a harder material in the rib and a softer material in the upper strip. Another possibility is for the upper limbs of the Y have inward deformations to captivate the elastomeric insert.
In another embodiment, the field limitation joint is a co-extrusion of a relatively rigid plastics material comprising the limbs of the Y and a less rigid plastics material between the upper limbs of the Y comprising the core.
Preferably, the joint has a rigid portion having a gauge width thicker than the lower limb of the Y and thinner than the free width of at least the distal ends of the upper limbs of the Y, and defining the design compressed width thereof. Ususally, the rigid portion will be a lateral swelling at the junction of the limbs of the Y.
The building elements will normally be tiles or other slab like elements such as terrazo which has sufficient rigidity to compress the core on fitting of the joint to the elements or the elements to the joint.